[Alt-photo] Cerium Introduction

jimbobnola at cox.net jimbobnola at cox.net
Sat Mar 5 22:20:23 UTC 2016

Hi Group,
I found that August and Louis Lumiere experimented with cerium salts for prints (1893), William Willis developed Aniline Black (1865, dichromate), and Thomas Manly developed Ozotype (1898, dichromate).  I combined these into Cerium Ozotype and Cerium Aniline Black (dicrhomate free processes).
Cerium IV salts (orange) are reduced to Cerium III (white) by UV.  Cerium IV forms a black pigment with ppd/catechol, which I believe is the same as or similar to Willis' Aniline Black.
Cerium IV strongly hardens gelatin, and Cerium III moderately hardens gelatin.  Cerium III oxalate is very insoluble.  These properties are used in Cerium Ozotype, a carbon process.
These are Positive processes; you start with black and UV removes the color to paper white highlights.  The challenge is to have a very uniform layer of cerium.  Agar coated on watercolor paper with a wire wound coating rod or fixed out silver-gelatin photo paper worked.  Your standard exposure is for paper white, and you use a Positive transparency for printing.
I will post the details if anyone is interested.
Jim Patterson, New Orleans

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